The Combination of the Tunnel View and Weight-Bearing Anteroposterior Radiographs Improves the Detection of Knee Arthritis.

Imaging used for the evaluation of knee pain has historically included weight-bearing anteroposterior (AP), lateral, and sunrise radiographs. We wished to evaluate the utility of adding the weight-bearing (WB) posteroanterior (PA) view of the knee in flexion. We hypothesize that (1) the WB tunnel view can detect radiographic osteoarthritis (OA) not visualized on the WB AP, (2) the combination of the AP and tunnel view increases the radiographic detection of OA, and (3) this may provide additional information to the clinician evaluating knee pain. We retrospectively reviewed the WB AP and tunnel view radiographs of 100 knees (74 patients) presenting with knee pain and analyzed for evidence of arthritis. The combination of the WB tunnel view and WB AP significantly increased the detection of joint space narrowing in the lateral (p < 0.001) and medial (p = 0.006) compartments over the AP view alone. The combined views significantly improved the identification of medial subchondral cysts (p = 0.022), sclerosis of the lateral tibial plateau (p = 0.041), and moderate-to-large osteophytes in the medial compartment (p = 0.012), intercondylar notch (p < 0.001), and tibial spine (p < 0.001). The WB tunnel view is an effective tool to provide additional information on affected compartments in the painful knee, not provided by the AP image alone.

Prospective Comparison of Blood Culture Bottles and Conventional Swabs for Microbial Identification of Suspected Periprosthetic Joint Infection.

BACKGROUND: Early, accurate detection of infection is vital to successful treatment of periprosthetic joint infection (PJI). Currently, no "gold standard" diagnostic testing exists. The goal of this prospective study was to compare the efficacy of a blood culture bottle system (BCBS) to commonly used culture swabs in confirming PJI in patients with high clinical suspicion. METHODS: Patients were selected for enrollment based on Musculoskeletal Infection Society guidelines for PJI. erythrocyte sedimentation rate and C-reactive protein were obtained before aspiration. Aspirated fluid was divided between BCBS, swab, and synovial fluid analysis. Forty-nine samples were analyzed. RESULTS: BCBS yielded 41 positive cultures vs 19 with swab (P < .0001), particularly with respect to Staphylococcus epidermidis. There were no false positive results in the BCBS group, using strict Musculoskeletal Infection Society guidelines. CONCLUSION: BCBS increased identification of pathogens in lower extremity PJI, providing clinicians with a low-cost, broadly-applicable test.

How are those "lost to follow-up" patients really doing? A compliance comparison in arthroplasty patients.

AIM: To determine whether there is a functional difference between patients who actively follow-up in the office (OFU) and those who are non-compliant with office follow-up visits (NFU). METHODS: We reviewed a consecutive group of 588 patients, who had undergone total joint arthroplasty (TJA), for compliance and functional outcomes at one to two years post-operatively. All patients were given verbal instructions by the primary surgeon to return at one year for routine follow-up visits. Patients that were compliant with the instructions at one year were placed in the OFU cohort, while those who were non-compliant were placed in the NFU cohort. Survey mailings and telephone interviews were utilized to obtain complete follow-up for the cohort. A χ(2) test and an unpaired t test were used for comparison of baseline characteristics. Analysis of covariance was used to compare the mean clinical outcomes after controlling for confounding variables. RESULTS: Complete follow-up data was collected on 554 of the 588 total patients (93%), with 75.5% of patients assigned to the OFU cohort and 24.5% assigned to the NFU cohort. We found significant differences between the cohorts with the OFU group having a higher mean age (P = 0.026) and a greater proportion of females (P = 0.041). No significant differences were found in either the SF12 or WOMAC scores at baseline or at 12 mo postoperative. CONCLUSION: Patients who are compliant to routine follow-up visits at one to two years post-operation do not experience better patient reported outcomes than those that are non-compliant. Additionally, after TJA, older women are more likely to be compliant in following surgeon instructions with regard to follow-up office care.

Impact of forestry practices at a landscape scale on the dynamics of amphibian populations.

Forest loss is a primary cause of worldwide amphibian decline. Timber harvesting in the United States has caused dramatic changes in quality and extent of forest ecosystems, and intensive forest management still occurs. Although numerous studies have documented substantial reductions in amphibian densities related to timber harvest, subsequent extinctions are rare. To better understand the population dynamics that have allowed so many amphibian species to persist in the face of widespread forest disturbance, we developed spatially explicit metapopulation models for four forest-dependent amphibian species (Lithobates sylvaticus, Ambystoma opacum, A. talpoideum, and A. maculatum) that incorporated demographic and habitat selection data derived from experiments conducted as part of the Land Use Effects on Amphibian Populations Project (LEAP). We projected local and landscape-scale population persistence under 108 different forestry practice scenarios, varying treatment (partial cut, clear-cut with coarse woody debris [CWD] removed, and clearcut with CWD retained), cut patch size (1, 10, or 50 ha), total area cut (10, 20, or 30%), and initial amphibian population size (5, 50, or 500 adult females per local breeding population). Under these scenarios, landscape-scale extinction was highly unlikely, occurring in < 1% of model runs and for only 2 of the 4 species, because landscape-scale populations were able to persist via dispersal even despite frequent local extinctions. Yet for all species, population sizes were reduced to -50% in all clear-cut scenarios, regardless of the size of harvested patches. These findings suggest that debate over timber harvesting on pool-breeding amphibian populations in the United States should focus not on questions of landscape-scale extinction but on the ecological consequences of dramatic reductions in amphibian biomass, including changes in trophic interactions, nutrient cycling, and energy transfer. Additionally, we conclude that amphibian declines and extinctions are far more likely to occur as a result of permanent habitat loss resulting from development than from the temporary degradation of habitat caused by current forestry practices.

Metal-on-metal hip resurfacing compared with total hip arthroplasty: two to five year outcomes in men younger than sixty five years.

PURPOSE: There are limited studies examining the long-term survivorship for the current generation of metal-on-metal hip resurfacing (MOMHR) implants in the young male population, and fewer studies have been published on prospectively collected outcomes data for total hip resurfacing in the USA. The purpose of this study was to demonstrate the efficacy of MOMHR in comparison with total hip arthroplasty (THA) using validated outcome measures, survivorship and complication rates. METHODS: The study prospectively followed 136 implants in 123 male patients <65 years, all with a primary diagnosis of osteoarthritis and similar comorbidities as determined by the American Society of Anesthesiologists (ASA) score. A single-surgeon cohort of 89 MOMHRs was compared with a similar cohort of 47 THAs. Outcomes were prospectively assessed with the Short-Form Health Survey of 12 questions (SF-12) and Western Ontario and McMaster Universities (WOMAC) questionnaires pre- and postoperatively at yearly intervals. Minimum follow-up was two years, and average follow-up was 3.9 years. RESULTS: Diagnosis, body mass index (BMI), American Association of Anesthesiologists (ASA) and pre-operative pain and function scores were not significantly different between groups. There was no difference in SF-12 scores postoperatively. At one and two years postoperatively, the MOMHR group had better WOMAC scores than the THA group, but no difference was seen at three to five years postoperatively. There were no revisions in either group over the study period. CONCLUSIONS: This study demonstrated good results for hip resurfacing in men <65 years five years postoperatively and similar function to THA patients.

Superficial wound closure complications with barbed sutures following knee arthroplasty.

As quality measures may be increasingly used in knee surgery reimbursement, an important focus in outcome assessment will shift toward minimizing complications and increasing efficiency in knee arthroplasty reconstruction. The purpose of this study was to evaluate the efficacy of barbed, absorbable sutures in closure of the longitudinal surgical incision following knee arthroplasty, using post-operative complication occurrences. In 416 operations, primary outcomes assessed were deep infection, superficial infection, dehiscence, or stitch abscesses. Secondary outcomes included self-limiting eschar, severe effusion, arthrofibrosis, and keloid formation. Evaluation of overall primary outcomes showed a higher rate of wound complications using barbed sutures (P < 0.001). With increased rates of infection and overall closure related complications, this study shows that barbed suture use for superficial closure after knee arthroplasty should be avoided.

Imageless computer navigation in total knee arthroplasty provides superior short term functional outcomes: a meta-analysis.

Computer navigation in total knee arthroplasty (TKA) is intended to produce more reliable results, but its impact on functional outcomes has not been firmly demonstrated. Literature searches were performed for Level I randomized trials that compared TKA using imageless computer navigation to those performed with conventional instruments. Radiographic and functional outcomes were extracted and statistically analyzed. TKA performed with computer navigation was more likely to be within 3° of ideal mechanical alignment (87.1% vs. 73.7%, P < .01). Navigated TKAs had a higher increase in Knee Society Score at 3-month follow-up (68.5 vs. 58.1, P = .03) and at 12-32 month follow-up (53.1 vs. 45.8, P < .01). Computer navigation in TKA provides more accurate alignment and superior functional outcomes at short-term follow-up.

Is the posterior cruciate ligament destabilized after the tibial cut in a cruciate retaining total knee replacement? An anatomical study.

INTRODUCTION/PURPOSE: Cruciate retaining total knee replacement has been shown to effectively improve pain and quality of life. Successful outcomes depend on many factors, including the maintenance of a competent posterior cruciate ligament. This study sought to anatomically analyze the percentage of PCL injured during a full transverse, tibial cut, thus altering normal function. MATERIALS AND METHODS: One hundred and thirty five consecutive knee MRIs taken from 2006 to 2011 were selected from a single surgeon's database for this study. Only subjects with non-arthritic knees were considered for this study; the lack of degenerative joint disease (DJD) was confirmed via a radiological report. The optimal view of the PCL's tibial attachment was observed using the sagittal view of the knee, with a T1 signal. One hundred and twenty two usable images were viewed electronically, and measurements were made using the standardized transverse cut implant guidelines. The percentage of PCL remaining following the cut was categorized into five different groups: 0% (no PCL undermined), 1-49%, 50-74%, 75-99% and 100% (PCL undermined entirely). RESULTS: Overall only 9.0% (n=11) would have not endured any damage to the PCL with a transverse tibial saw cut, while 79.6% (n=98) would have had 50% or more of the PCL undermined. Of the 98 patients with more than 50% resected, 52.1% (n=51 patients) presented complete destabilization of the PCL. The percentage of PCL destabilized was not significant across age groups (p=0.280), gender (p=0.586), or operative side (p=0.460). CONCLUSION: Independent of age, gender, and operative side, a majority of PCLs are more than 50% destabilized following the standard transverse tibial cut. LEVEL OF EVIDENCE: II.

Predicting femoral head diameter and lesser trochanter to center of femoral head distance: a novel method of templating hip hemiarthroplasty.

Lesser-trochanter-to-center-of-femoral-head-distance (LTCHD) is commonly used in hip reconstruction. Demographic and radiographic variables were analyzed to predict the LTCHD and femoral head size (FHS). Two hundred twenty six patients after hip arthroplasty and 136 patients after hip hemiarthroplasty (HA) were retrospectively reviewed. Five variables significantly affected the LTCHD and four affected the FHS. For LTCHD, it was relative neck length (RNL), gender, height, race, age and weight. For FHS it was gender, height, age and race. The average predicted LTCHD was within 2.86 mm, and the FHS was 1.63 ± 1.10mm of the intra-operative measurements. By using our regression formulas the LTCHD and FHS can be calculated preoperatively to help improve precision in leg length and offset reconstruction.

Longitudinal evaluation of time related femoral neck narrowing after metal-on-metal hip resurfacing.

AIM: To track the short-term neck narrowing changes in Birmingham metal-on-metal hip resurfacing (MOMHR) patients. METHODS: Since 2001, the Center for Hip and Knee Replacement started a registry to prospectively collect data on hip and knee replacement patients. From June 2006 to October 2008, 139 MOMHR were performed at our center by two participate surgeons using Birmingham MOMHR prosthesis (Smith Nephew, United States). It is standard of care for patients to obtain low, anteriorposterior (LAP) pelvis radiographs immediately after MOMHR procedure and then at 3 mo, 1 year and 2 year follow up office visits. Inclusion criteria for the present study included patients who came back for follow up office visit at above mentioned time points and got LAP radiographs. Exclusion criteria include patients who missed more than two follow up time points and those with poor-quality X-rays. Two orthopaedic residency trained research fellows reviewed the X-rays independently at 4 time points, i.e., immediate after surgery, 3 mo, 1 year and 2 year. Neck-to-prosthesis ratio (NPR) was used as main outcome measure. Twenty cases were used as subjects to identify the reliability between two observers. An intraclass correlation coefficient at 0.8 was considered as satisfied. A paired t-test was used to evaluate the significant difference between different time points with P < 0.05 considered to be statistically significant. RESULTS: The mean NPRs were 0.852 ± 0.056, 0.839 ± 0.052, 0.835 ± 0.051, 0.83 ± 0.04 immediately, 3 mo, 1 year and 2 years post-operatively respectively. At 3 mo, NPR was significantly different from immediate postoperative X-ray (P < 0.001). There was no difference between 3 mo and 1 year (P = 0.14) and 2 years (P = 0.53). Femoral neck narrowing (FNN) exceeding 10% of the diameter of the neck was observed in only 4 patients (5.6%) at two years follow up. None of these patients developed a femoral neck fracture (FNF). CONCLUSION: Femoral neck narrowing after MOMHR occurred as early as 3 mo postoperatively, and stabilized thereafter. Excessive FNN was not common in patients within the first two years of surgery and was not correlated with risk of FNF.

Higher body mass index leads to longer operative time in total knee arthroplasty.

Obesity has been shown to be a risk factor for degenerative knee arthritis and its incidence is increasing in epidemic proportions. Obesity has also been shown to be a risk factor for surgical complications associated with total knee replacement (TKR) surgery. There have been no prior investigations examining the relationship between body mass index (BMI) and surgical time during TKR. Two hundred and seventy three patients were evaluated and stratified by BMI. There was a direct linear relationship between BMI and operative time. In addition, the higher the BMI group, the younger the age at surgery, and obese class III patients experienced a higher rate of early post-operative complication. Therefore, patients should be counseled that obesity prior to TKR surgery might lead to a longer operative time and any sequelae associated with further exposure of the operative wound, especially with regard to higher rates of prosthetic joint infection (PJI).

Terrestrial habitat selection and strong density-dependent mortality in recently metamorphosed amphibians.

To predict the effects of terrestrial habitat change on amphibian populations, we need to know how amphibians respond to habitat heterogeneity, and whether habitat choice remains consistent throughout the life-history cycle. We conducted four experiments to evaluate how the spatial distribution of juvenile wood frogs, Rana sylvatica (including both overall abundance and localized density), was influenced by habitat choice and habitat structure, and how this relationship changed with spatial scale and behavioral phase. The four experiments included (1) habitat manipulation on replicated 10-ha landscapes surrounding breeding pools; (2) short-term experiments with individual frogs emigrating through a manipulated landscape of 1 m wide hexagonal patches; and habitat manipulations in (3) small (4-m2); and (4) large (100-m2) enclosures with multiple individuals to compare behavior both during and following emigration. The spatial distribution of juvenile wood frogs following emigration resulted from differences in the scale at which juvenile amphibians responded to habitat heterogeneity during active vs. settled behavioral phases. During emigration, juvenile wood frogs responded to coarse-scale variation in habitat (selection between 2.2-ha forest treatments) but not to fine-scale variation. After settling, however, animals showed habitat selection at much smaller scales (2-4 m2). This resulted in high densities of animals in small patches of suitable habitat where they experienced rapid mortality. No evidence of density-dependent habitat selection was seen, with juveniles typically choosing to remain at extremely high densities in high-quality habitat, rather than occupying low-quality habitat. These experiments demonstrate how prediction of the terrestrial distribution of juvenile amphibians requires understanding of the complex behavioral responses to habitat heterogeneity. Understanding these patterns is important, given that human alterations to amphibian habitats may generate extremely high densities of animals, resulting in high density-dependent mortality.

Preservation of an aberrant left hepatic artery during laparoscopic nissen fundoplication.

OBJECTIVE: Laparoscopic Nissen fundoplication is performed in neonates and children for significant gastroesophageal reflux. An aberrant left hepatic artery encountered during laparoscopic Nissen fundoplication makes dissection around the esophageal hiatus more difficult if the artery is not transected. Although some suggest division of the aberrant left hepatic artery, this is associated with risk of significant hepatic injury from ischemia. We routinely preserve the aberrant left hepatic artery and sought to determine (1) the incidence of aberrant left hepatic artery and (2) the results following preservation of the aberrant left hepatic artery. METHODS: Between January 2000 and October 2002, 195 laparoscopic Nissen fundoplications were performed. We documented intraoperative findings of each procedure, and reviewed postoperative radiographic studies and clinic visits. RESULTS: In 30 patients (15%), an aberrant left hepatic artery was identified. All dissections were performed laparoscopically with the Nissen fundoplication positioned cephalad to the aberrant left hepatic artery. Postoperatively, 2 patients (6%) have had evidence of wrap failure. The remainder of the patients has had normal radiographic studies or no clinical evidence of reflux during clinic visits. CONCLUSION: During laparoscopic Nissen fundoplication in neonates and children, an aberrant left hepatic artery may be encountered in approximately 15% of patients. When an aberrant left hepatic artery is identified, it should be preserved to avoid the potential risk of hepatic ischemic injury.